The Collaborative International Dictionary of English v.0.48:

Expand \Ex*pand"\, v. i.
   To become widely opened, spread apart, dilated, distended, or
   enlarged; as, flowers expand in the spring; metals expand by
   heat; the heart expands with joy. --Dryden.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Expand \Ex*pand"\, v. t. [imp. & p. p. Expanded; p. pr. & vb.
   n. Expanding.] [L. expandere, expansum; ex out + pandere to
   spread out, to throw open; perh. akin to E. patent. Cf.
   Spawn.]
   1. To lay open by extending; to open wide; to spread out; to
      diffuse; as, a flower expands its leaves.
      [1913 Webster]

            Then with expanded wings he steers his flight.
                                                  --Milton.
      [1913 Webster]

   2. To cause the particles or parts of to spread themselves or
      stand apart, thus increasing bulk without addition of
      substance; to make to occupy more space; to dilate; to
      distend; to extend every way; to enlarge; -- opposed to
      contract; as, to expand the chest; heat expands all
      bodies; to expand the sphere of benevolence.
      [1913 Webster]

   3. (Math.) To state in enlarged form; to develop; as, to
      expand an equation. See Expansion, 5.
      [1913 Webster]

WordNet (r) 3.0 (2006):

expand
    v 1: extend in one or more directions; "The dough expands" [syn:
         expand, spread out] [ant: contract, shrink]
    2: become larger in size or volume or quantity; "his business
       expanded rapidly"
    3: make bigger or wider in size, volume, or quantity; "expand
       the house by adding another wing"
    4: grow vigorously; "The deer population in this town is
       thriving"; "business is booming" [syn: boom, thrive,
       flourish, expand]
    5: exaggerate or make bigger; "The charges were inflated" [syn:
       inflate, blow up, expand, amplify]
    6: add details, as to an account or idea; clarify the meaning of
       and discourse in a learned way, usually in writing; "She
       elaborated on the main ideas in her dissertation" [syn:
       elaborate, lucubrate, expatiate, exposit, enlarge,
       flesh out, expand, expound, dilate] [ant:
       abbreviate, abridge, contract, cut, foreshorten,
       reduce, shorten]
    7: expand the influence of; "The King extended his rule to the
       Eastern part of the continent" [syn: extend, expand]

Moby Thesaurus II by Grady Ward, 1.0:

119 Moby Thesaurus words for "expand":
   add to, adulterate, aggrandize, amplify, attenuate, augment,
   balloon, beef up, bloat, blow up, bolster, boost, branch,
   branch out, broaden, build, build up, bulk, bulk out, complete,
   crescendo, cut, deal in generalities, deepen, deploy, descant,
   detail, develop, dilate, dilute, discourse, disperse, distend,
   ecumenicize, elaborate, embellish, enlarge, enlarge upon,
   enter into detail, etherealize, evolve, exalt, expatiate,
   explicate, extend, fan, fan out, fatten, fill out, flare,
   generalize, globalize, go into, greaten, grow, heighten, hike,
   hike up, huff, increase, inflate, jack up, jump up, labor,
   lengthen, magnify, make a generalization, maximize, mount,
   multiply, mushroom, open, open up, outspread, outstretch, overgrow,
   overrun, parlay, particularize, prolong, protract, puff, puff up,
   pump, pump up, put up, pyramid, raise, ramify, rarefy,
   rehearse in extenso, relate at large, snowball, spell out, splay,
   spraddle, sprangle, sprawl, spread, spread like wildfire,
   spread out, stretch, subtilize, sufflate, swell, thicken, thin,
   thin out, tumefy, unfold, universalize, up, upsurge, vise, water,
   water down, wax, widen, work out